1. Field of the Invention
The present invention relates to an electromagnetic clutch, and more preferably, to an electromagnetic clutch employed in a compressor that is assembled into an air conditioner in a vehicle or the like.
2. Description of the Related Art
FIG. 16 is a view in longitudinal section showing an example of a conventional electromagnetic clutch.
This electromagnetic clutch 100 is provided in a compressor, such as an air conditioner in a vehicle or the like. Electromagnetic clutch 100 mechanically and intermittently connects this compressor and a driving source not shown in the Figure. Electromagnetic clutch 100 is disposed in the nose portion 101 of the front case of the compressor.
A driving rotor 103 is supported in a freely rotating manner at the outer periphery of nose portion 101 via clutch shaft bearing 102. A coil 104 is included inside driving rotor 103. Armature plate 105 is coaxially disposed so as to be facing said driving rotor 103.
Hub 106 is fixed in place by a nut 107 to the projecting portion of drive shaft 112 of the compressor. One end of connecting plate 108 is fixed in place to this hub 106 by rivet 110, while the other end is fixed to armature plate 105 via rivet 109. Electromagnetic clutch 100 is composed of clutch shaft bearing 102, driving rotor 103, coil 104, armature plate 105, hub 106, connecting plate 108, and rivets 109 and 110 as main parts thereof.
A belt pulley 111 is provided at the outer periphery of driving rotor 103 and is connected to a driving source such as an engine via a V belt that is wrapped around belt pulley 111 but is not shown in the figures.
In an electromagnetic clutch 100 of this design, the driving rotor 103 is connected to a driving source such as an engine, so that it is constantly rotating when the driving source is rotating. When electricity is sent through coil 104 and excites it in this state, armature plate 105 attaches to driving rotor 103 as a result of the magnetic force of coil 104. A rotating torque of the driving source is communicated to drive shaft 111 via, in sequence, driving rotor 103, armature plate 105, rivet 109, connecting plate 108, rivet 110, and hub 106. Drive shaft 112 of the compressor element is rotated as a result.
In this state, when electricity ceases to be sent through coil 104, armature plate 105 separates from driving rotor 103, and the transmission of power to drive shaft 112 is interrupted.
In the electromagnetic clutch 100, the armature plate 105 is made of metal and is formed as a thick plate having a unitary structure. Driving rotor 103 is also formed as a unitary structure from a metal material. When electricity is passed through coil 104 and armature plate 105 is attached to driving rotor 103 due to the magnetic force of coil 104, armature plate 105 is coupled to driving rotor 103 at high speed so as to minimize the relative slipping time between armature plate 105 and the end face of driving rotor 103. For this reason, a problematic noise is generated when electricity is sent through coil 104, so that coil 104 is excited and the armature plate 105 makes contact with an end face of the driving rotor 103.
The present invention was conceived in view of the above-described problems, and has as its objective the provision of an electromagnetic clutch capable of decreasing the noise generated when the armature plate makes contact with the driving rotor. The present invention further aims to provide a compressor equipped with this electromagnetic clutch.
The electromagnetic clutch in the present invention comprises a driving rotor that is connected so as to be linked to a driving source and that includes a coil, and an armature having an armature plate that is disposed facing this driving rotor and having the same axis of rotational thereas, wherein, when a voltage is applied to excite the coil, the end face of the driving rotor and the armature plate are attached or separated by the coil""s magnetic force, thereby intermittently coupling the driving rotor and the armature. In said electromagnetic clutch, the armature plate comprises a plurality of plate members laminated together, and at least a part of each of the plate members being connected the other plate members.
In this electromagnetic clutch, the armature plate is formed by laminating together a plurality of plate members. As a result, air layers are formed in between each of the plate members. For this reason, a force generated when the armature plate makes contact with the end face of the driving rotor is absorbed and reduced through the vibration of the individual plate members of the armature plate.
In addition, because the armature plate comprises a plurality of plate members laminated together, the armature plate is less rigid as compared to conventional armature plates which consist of a thick plate formed as a unitary structure. Thus, the force generated when the armature plate makes contact with the end face of the driving rotor is absorbed and reduced.
In the electromagnetic clutch, each of the plate members has the same thickness.
Because each of the plate members is of equal thickness in this electromagnetic clutch, numerous plate members can be formed easily. As a result, the cost of the armature plate is decreased.
In said electromagnetic clutch, among the various plate members, the plate member that comes in contact with the end face of the driving rotor is of a different thickness than the other plate members.
The magnetic force generated by the armature plate is controlled by on the thickness of the plate member that comes in contact with the driving rotor. Accordingly, when the thickness of the plate member that comes in contact with the end face of the driving rotor is increased in this electromagnetic clutch, the magnetic flux generated by the coil passes easily through the plate members. Thus, the magnetic force generated at the armature plate becomes greater, and, as a result, the clutch torque increases.
Conversely, if the plate that comes in contact with the end face of the driving rotor is made thinner, then the plate members are less rigid. Therefore, the force generated when the armature plate makes contact with the end face of the driving rotor is reduced.
In the electromagnetic clutch, among the plate members, the plate member that comes in contact with the end face of the driving rotor is thicker than the other plate members.
Because the plate member that comes in contact with the end face of the driving rotor is in sliding contact with the end face of the driving rotor, it experiences more severe abrasion than the other plate members. Accordingly, in this electromagnetic clutch, the plate member that comes in contact with the end face of the driving rotor is made thicker than the other plate members.
In the electromagnetic clutch, the various plate members forming the armature plate are roughly ring-shaped and made of a metal material, and are fixed in place by welding at a plurality of sites on the outer periphery, or on the outer and inner peripheries, of the plate members.
By suitably welding a plurality of sites on the outer periphery, or on the outer and inner peripheries, of the plate members, the various plate members are conveniently fixed in place.
In addition, in the electromagnetic clutch in the present invention, the various plate members forming the armature plate are roughly ring-shaped, and are fixed in place by caulking at a variety of sites on the end face of the plate members.
By employing caulking, it is possible to fix the plate members securely without carrying out a thermal treatment such as welding.
The electromagnetic clutch comprises a driving rotor, that includes a coil and is connected so as to be linked to a driving source, and an armature, that has an armature plate that is disposed so as to face the driving rotor and has the same axis of rotation thereas, and the end face of the driving rotor and the armature plate are attached together or are separated by the coil""s magnetic force when the coil is excited due to voltage impression, thereby intermittently linking and connecting the driving rotor and the armature. In this electromagnetic clutch, the driving rotor has a main body portion formed in a unitary manner and a wall portion that forms the end face of the driving rotor, the wall portion comprises laminating a plurality of plate members, and at least a part of each of said plate members being connected to the other plate members.
The wall portion forming the end face of the driving rotor in this electromagnetic clutch is formed by laminating a plurality of plate members together. As a result, air layers are formed between each of the plate members, and a driving rotor end face is formed that has a low eigenvalue (spring constant). For this reason, the force generated when the end face of the driving rotor couples with the armature plate is absorbed and reduced due to the vibration of the individual plate members that form the wall portion on the end face side of the driving rotor.
In addition, the wall portion forming the end face of the driving rotor comprises a plurality of plate members laminated together. Thus, the driving rotor end face is less rigid than a conventional driving rotor end face that is formed to have a unitary structure. Thus, the force generated when the armature plate makes contact with the end face of the driving rotor is reduced.
In the electromagnetic clutch, each of the plate members has the same thickness.
By forming each of the plate members to have the same thickness in this electromagnetic clutch, a plurality of plate members can be easily formed. Thus, the cost of the driving rotor can be reduced.
In the electromagnetic clutch, among the plate members, the plate member that comes in contact with the armature plate is thicker than the other plate members.
The plate member that comes in contact with the armature plate is in sliding contact with the armature plate, so that it experiences more severe abrasion as compared to the other plate members. According, in this electromagnetic clutch, the plate member that comes in contact with the armature plate is thicker than the other plate members.
Further, in the present invention, each of the plate members is roughly ring-shaped and is formed of a metal material, and welding is performed to a plurality of sites on the outer periphery of the plate members or caulking is performed to outer peripheral sites on the end face of each of the plate members to fix the plate members to the outer peripheral side of the main body portion; and/or welding is performed to a plurality of sites on the inner periphery of the plate members or caulking is performed at inner peripheral sites on the end face of each of the plate members to fix the plate members to the inner peripheral side of the main body portion.
By welding or caulking on the outer peripheral side and/or the inner peripheral side of the plate members, each of the plate members can be conveniently fixed in place to the main body portion of the driving rotor.
In addition, in the present invention, the provision of the above-described armature plate and driving rotor.
In present invention, in a compressor for compressing a fluid using a compressor element, the power from the driving source that is mechanically connected to the driving rotor via the above-described electromagnetic clutch is communicated to the drive shaft of the compressor element that is mechanically connected to the armature.